A fuel cell is a cell that converts chemical energy into electrical energy through the electrochemically reaction between hydrogen and oxygen, and hydrogen obtained by reforming city gas and the like is utilized as the hydrogen source.
In the steam reforming reaction to obtain hydrogen by reforming city gas and the like, a reaction to produce hydrogen (H2) by adding steam to a hydrocarbon (CnHm) that is the main component of city gas and by chemically reacting them as described in the following Formula (1) using a fuel reforming catalyst proceeds as the main reaction. In addition, carbon monoxide (CO) obtained by the reaction of Formula (1) is bonded to a great amount of steam so that a reaction to produce hydrogen through a water-gas shift reaction further proceeds (see Formula (2)).CnHm+nH2O→nCO+(m/2+n)H2  (1)CO+H2O→CO2+H2  (2)
As the reforming catalyst used in such a steam reforming reaction, for example, a steam reforming catalyst of a hydrocarbon obtained by supporting zirconium oxide produced from zirconia sol as a precursor and a ruthenium component on aluminum oxide containing alkaline earth metal aluminate is disclosed (Patent Document 1).
In Patent Document 2, a hydrogen producing catalyst obtained by supporting a catalytically active species on a support containing a composite oxide powder that is formed by dispersing both ceria and alumina in a nm scale is disclosed as a catalyst for producing hydrogen from a gas containing a hydrocarbon, oxygen, and steam.
In addition, in Patent Document 3, a hydrogen producing catalyst obtained by supporting a catalytically active species on a support containing a composite oxide that is formed by dispersing ceria and zirconia in a nano-scale is disclosed as a catalyst for producing hydrogen from a gas containing a hydrocarbon.
In Patent Document 4, a fuel reforming catalyst in which at least one active component selected from the group consisting of ruthenium and rhodium is supported on a support containing a first oxide of cerium oxide and at least one second oxide selected from the group consisting of aluminum oxide and zirconium oxide is disclosed.
In Patent Document 5, a reforming catalyst for producing hydrogen is disclosed which is a steam reforming catalyst formed by containing a precious metal component including at least one species of ruthenium, rhodium, or platinum and a rare earth metal in an alumina support and in which the product of the content (% by mass) of the precious metal component contained in the catalyst with the dispersity (%) of the precious metal component is 100 or more and the dispersity (%) of the precious metal component is 70% or less.
In Patent Document 6, a steam reforming catalyst is disclosed which contains a support containing a composite oxide in which both of ceria and alumina are dispersed in a nano-scale and at least one species of metal element which is supported on the support and belongs to the group 8 to the group 10 in the long form periodic table.
In Patent Document 7, a fuel reforming catalyst is disclosed which is a fuel reforming catalyst formed by supporting a precious metal catalyst on a support composed of γ-alumina and in which cerium oxide of 5 to 30% by mass of the support is supported on the support.